Includes a `readingTime` field in seconds for every `Post` object response.

README.md

WPGraphQL Post Reading Time

Includes a readingTime field in seconds for every Post object response.

Usage

1. Download this ZIP
2. Upload to plugins
3. Activate it

wpgraphql-reading-time.php

<?php

/**
 * Plugin Name:     WPGraphQL Post Reading Time
 * Plugin URI:      https://gist.github.com/lightningspirit/a316117fbb9294da0d15f57553875033
 * Description:     Includes a `readingTime` field in seconds for every `Post` object response.
 * Author:          Move Your Digital, Inc.
 * Author URI:      https://moveyourdigital.com
 * Version:         0.1.0
 *
 * @package         WPGraphQL_Post_Reading_Time
 */

/*
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

// If this file is called directly, abort.
if (!defined('WPINC')) {
  die;
}

/**
 * Get reading time for a post.
 *
 * @param \WP_Post|int $post The post object or ID.
 * @return float The number of minutes
 */
function get_reading_time( \WP_Post|int $post ) {
	$post         = get_post( $post );
	$post_content = get_the_content_plaintext( $post );
	$word_count   = str_word_count( $post_content );

	$word_average = apply_filters( 'average_reading_words_per_minute', 300 );
	$minutes      = ceil( $word_count / $word_average );

	return apply_filters( 'post_reading_time', $minutes, $post, $word_average );
}

add_action('graphql_register_types', function () {
  register_graphql_fields(
    'Post',
    [
      'readingTime' => [
        'description' => __('Estimated post reading time', 'contasconnosco'),
        'type' => 'int',
        'resolve' => function (WPGraphQL\Model\Post $post) {
          return get_reading_time( $post );
        },
      ],
    ],
  );
});